[ExI] fermi flood was: RE: California storms

[Kelly Anderson]

I listened to this a month ago... about how the silt from the
Mississippi has been filling up the gulf of mexico...

https://www.youtube.com/watch?v=y2Qqslr5ytY&t=1274s

You might find it interesting just how much is down there.

On Tue, Feb 6, 2024 at 6:18 AM spike jones via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
>
>
>
> -----Original Message-----
> From: spike at rainier66.com <spike at rainier66.com>
> ...
>
> >...Consequently... plenty of people come to the USA and choose homeless
> here rather than homeful wherever they come from.  If one is going to live
> outdoors, an overpass or under a bridge makes perfect sense...The masses
> want freedom and capitalism, even if it means they must camp out here to get
> there.  spike
>
>
> I have been all over the map on this one, so I decided to post something
> over on a yet-uncommented part of the thought-map.
>
> The high schools play a game named for Enrico Fermi who was really good at
> this: estimating the order of magnitude.  An example of a fermi question
> would be: How many neutrons are in a fig newton?
>
> A good player would estimate its mass at about 10 to 20 grams, mostly
> carbon, a mole of carbon is about 12 grams, so about a mole times six
> neutrons per carbon atom, so 3.6E24 neutrons approximately, and depending on
> how you estimate mass, the answer might be either 24 or 25.
>
> Local flooding: there is a footbridge across the local waterway.  I was over
> there during last year's rains and noticed that the water is the color of
> chocolate milk.  I found a cup and scooped out a water sample, let it settle
> and observed that you aren't far off if you estimate the water is 10%
> sediment by mass, perhaps 5% by volume.  There really is that much silt and
> soil washing down that channel.
>
> I was over there yesterday and estimated, Fermi style, the average depth
> across there, about a meter, and its width, about ten meters.  When the
> water is that color, as it is now, the flow rate is likely higher than a
> meter a second, but a meter per second as a Fermi-ey estimate will get you
> there.  So... after a hard rain, as we have been having all week, about ten
> cubic meters per second flow rate down that channel, at about 10% silt.
>
> Fermi question: in kg, the mass of silt carried by the Penitentia Creek
> after a hard rain per second.  Answer: 3.  10^3 kg per second.  A ton of
> silt per second.  This process can go on for hours, or days.
>
> Second question: where does all that silt go?
>
> It gives one a new sense of how deltas form, and what happens when we need
> the space to build homes, so we defeat nature's course and build a single
> narrow channel where a vast river delta used to be.
>
> Prediction: eventually that channel will silt up and restrict flow rate,
> causing water to rise along the course of that river.  Consequence: the
> homeless living under those bridges will get washed out more regularly.
>
> spike
>
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